Mobile phone and checklist vector illustration, flat cartoon smartphone with paper document and to do list checkboxes, concept of survey, online quiz, completed things, done test, cellphone feedback 手机和清单向量例证, 平板卡通智能手机与纸质文档和做列表复选框, 调查的概念, 在线测验, 完成的事情或完成测试, 手机反馈